Circuit-changer for telephone-switchboards.



No. 764,143. PATENTED JULY 5, 1904. W. E. MOOORMIOK.

GIRGUIT CHANGER FOR TELEPHONE SWITGHBOARDS.

APPLICATION FILED AUG. 26. 1901.

N0 MODEL. 2 sums-sum 1.

No. 764,143. PATENTED JULY 5, 1904.

W. E. MCCORMICK. CIRCUIT CHANGER FOR TELEPHONE. SWITGHBOARDS.

APPLICATION FILED AUG. 26, 1901.

2 SHEETS-SHEET Z K0 MODEL.

I $7 55%] 6% izflmww UNITED STATES Patented July 5, 1904.

PATENT OEEICE.

IVILLIAM E. MCCORMICK, OF CHICAGO, ILLINOIS, ASSIGNOR TO INTER- NATIONAL TELEPHONE MANUFACTURING COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

CIRCUIT-CHANGER FOR T ELEPHONE-SWITCHBOARDS.

SPECIFICATION forming part of Letters Patent No. 764,143, dated July 5, 1904. Application filed August 26, 1901. Serial No. 73,363. (No model.)

T0 (6 whom, it may concern.-

Be it known that I, VVILLIAM E. McCon- MICK, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Circuit-Changers for' Telephone-Switchboards; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, which form a part of this specification.

This invention relates to a switching apparatus for including the different instrumentalities of an operators telephone set with any or removing it from any of a number of subscribers lines terminating at the central office of a telephone-exchange, and is designed for the operators use in connection with any number of line connections on a switchboard, which may be of any ordinary or suitable construction, and enables the operator upon receiving'a signal or call by means of any suitable device to ascertain the subscribers wants and communicate the same to any of various other subscribers in order that the desired connections may be made, thus constituting a combined ringing and listening switch for the use of the telephone operator at the central station.

It has for its object to produce a simple and eflicient combined ringing and listening switch or circuit-changer, and the essential features thereof and the mode of operation will be hereinafter particularly set forth and then clearly defined by the claims.

In the accompanying drawings, Figure 1 is a side elevation of my improved circuitchanger with the key in its normal position. Fig. 2 is a longitudinal sectional view of certain of the parts shown in Fig. 1, with the key shown in side elevation, and illustrating by dotted lines the positions to which it is shifted by the operator. Fig. 3 is a rear elevation of the parts shown in Fig. 1. Fig. 4c is a section on the line A A of Fig. 2, showing the relative arrangement and organization of the parts constituting the ringing side of the switch or circuit-changer, the normal position of the key being shown in full lines and its second position in dotted lines. Fig. 5 is a section on the line B B of Fig. 2, showing the relative arrangement and organization of the parts constituting the listening side of the switch or circuit-changer, the normal position of the key being shown in full lines and its second position in dotted lines. Fig. 6 is a diagrammatic view showing the relation of the terminals or contact-strips on the listen- Y ing side of the switch when in their normal or unused position. Fig. 7 is a similar view of the parts shown in Fig. 6 and illustrates their relation when the key is shifted to operative position, which is that shown by the dotted line in Fig. 5. Fig. 8 is a diagrammatic view showing the relation of the terminals or contact-strips on the ringing side of the switch when the parts are in their normal or unused position. Fig. 9 is a similar view of the parts shown in Fig. 8, but illustrating the relation of the parts when the key is shifted to its position of use, which is that shown by the dotted lines in Fig. 4. Fig. 10 is a diagrammatic view showing the circuits in connection with which my improved circuitchanger or switch is used.

In the drawings the numeral 1 designates the body of the circuit changer or switch, which is composed of a rectangular plate adapted to be let into the woodwork of the switchboard and carries a suitable base of insulating material near one of its ends and a key near its other end. The insulating-base for retaining the contacts hereinafter described is supported upon the body in any suitable manner and preferably by a yokeshaped bracket 2, which is attached to the edges of the body by suitable screws 3 and which depends below the body a suitable distance to support the base in proper relation to the other parts. terial, which is supported upon the bracket and which in turn supports the contact strips or terminals, is preferably made in sections 4 and 5, as shown most clearly in Fig. 2, and

The base of insulating main order to retain the parts rigidly in proper position I prefer to use a screwbolt 6, which passes through the several parts in the manner shown in Fig. 2. Each of the blocks 4 and 5 comprising the base is provided in its lower edge with a series of transverse slots or kerfs to receive the contact-strips, the upper block 4 being provided with six such slots, arranged in groups of three each, and the lower block 5 being provided with four such slots, arranged in groups of two each, although for convenience in the preparation of these blocks each may be provided with the same number of slots, in which case the inner pair of slots will not be utilized in the lower block, as clearly shown in Fig. 3. The slots extend across the lower edge of the blocks, and when the blocks are assembled in position, as shown in Fig. 2, the uncut upper edge of the lower block 5 will serve to retain the contact-strips in the slots or kerfs of the upper block, and an auxiliary insulating-strip 7 will serve the same function with reference to the contactstrips of the lower block 5, the organization and relative arrangement of these parts when properly assembled being clearly shown in the various figures of the drawings.

The upper block 4 is provided with three pairs of contact-strips g g, 00, and a a, comprising the ringing bank or range, arranged in groups of three upon each side of its center line, the intermediate strip, as c and c, of each group extending a slight distance beyond the forward ends of the adjacentcontacts and in position to be engaged by an insulated button mounted upon one branch of the key. The contact-strips of this range or bank comprise the terminals and switching elements representing the ringing side of the switch, and at their rear ends are provided with suitable soldering-terminals arranged preferably, out of alinement with each other, as by bending the outer and inner strips of each group downwardly and upwardly, respectively, as shown in Figs. 1 and 3. The terminals of the strips g and g lead to the magneto-generator or to any other suitable source of electrical supply, the strips 0 and c are in electrical connection with the cord conductors of the ringing-plug p and the strips (,4 and rt with those of the answering-plug p, as by means of the conductors w and 20, all as shown in Fig. 10.

The lower block 5 of the base is provided with the listening bank or range, composed of two pairs of contact-strips, one pair, as t and t, leading to the operators telephone set, and the other pair, as c and 0 leading to the cord conductor of the answering-plug p and being preferably permanently tied to and in electrical connection with the strips a and a, respectively, on the ringing side by means of the ordinary cord connections w and w, all as shown in Fig. 10. The strips of each pair are arranged on the opposite sides of the median line of the body, and the strips 0 and c extend forward beyond the strips 1? and 25 and are of substantially the same length as the strips 0 and c on the ringing side. The two banks or ranges of contact-strips are thus mounted one above the other, the strips constituting the contacts of the ringing side of the circuitchanger lying in a plane above the strips constituting the contacts of the listening side of the switch, and each series is'divided into opposite groups and has a pair of strips extending forward beyond the other strips, where they are provided with inwardly-facing and oppositely-disposed cam-faces, as shown in Figs. 4 and 5, in substantially the same vertical lines. The several strips of the two series are preferably resilient, and the extended strips are preferably somewhat stronger than the others, as they comprise the spring-strips of the switch, which are the ones that receive the most strain and are most employed as switching agents, besides performing the ad- I ditional functions of holding the key out of and returning it to its normal position, as will be hereinafter described. By arranging the banks or ranges of contact strips or terminals at or near the same end of the plate or body all the soldering-tcrminals employed are at one end of the switch, so that but one cable is requiredfor wiring all these terminals in stead of two, as where the terminals are at opposite sides of the switch. Each pair of these longer spring-strips extends into the path of one leg of a pivoted key K. This key or camlever is preferably mounted near one end of the body in such manner as to be shifted to either side of a normal central position, and is provided with two depending legs Zr and 72, of unequal length, which work through a slot in the body and are movable in a common plane. Each of these depending legs is provided with a spherical insulating-tip 7: and k, respectively, and the arrangement and organization is such that the tip it lies within the cams of the contact-strips c and c" and the tip 7:: lies without the cams of the contactstrips 0 and 0, each tip being in line with and normally resting against the cam-faces with which it cooperates in the manner shown in Figs. 2, 4c, and 5. The spring-strips form spring-jaws, and the mechanical feature of this organization is that when the key is shifted to the position indicated by the letter 1/ the tip A does not pass within its cooperating jaws far enough to bring its transverse line of greatest width or vertical diameter coincident with or beyond the apex of or the shortest distance between the cam-faces of the springs c and 0, whereby when the operator releases the key the resilient force of these springs will cause the outer flared ends of the eam-faces to coact with the curved or rounded face of the tip to return the key to normal position, and when the key is shifted to the position indieated by the letter zthe tip ir passes within its associated spring-jaws far enough to permit the apex ofthe cam-faces to bear upon it at or behind its corresponding diameter, whereby the key is retained in the position 2, being held against the outer end of its slot in the body. The cam lever or key is thus arranged in the median line of the contact-strips and central to both banks, and by reason of its forked construction one leg opens the first or upper set of spring-strips from the front, while the other leg passes through between the groups of this bank and opens the second or lower set of spring-strips from the rear.

The electrical features of this organization are apparent from Figs. 6 to 10 of the drawings. The normal position of the several parts and their connections are shown in Fig. 10, which illustrates diagrammatically the various parts. The listening side of the switch is shown more in detail in Figs. 6 and 7, the former showing the relation of the contacts when the key is in its normal position, as shown in full lines in other views, and the latter showing the spring-contacts c and c in position to engage the contacts z and 15 when the key is shifted to position .2, whereby the operators set is placed in electrical connec-v tion with the answering-plug p to enable the operator to communicate with the calling subscriber. While the conversation is beingheld the spring-jaws 0 and 0 hold the key in position 2, as above explained, whereby the operator is free to attend to the several succeeding steps or operations required to connect the calling and called subscribers. This feature of locking the key in listening position is therefore important. The ringing side of the switch is shown in detail inFigs. 8 and 9. The spring-contacts c and c normally are in electrical connection with the contacts a and (4, whereby the answering and connecting plugs p and 1), respectively, are electrically connected, as shown in Fig. 10. l/Vhen the operator has ascertained the number of the called subscriber, he inserts the plug p into the corresponding jack and presses the key to position y, whereby the contacts 0 and 0 are shifted to the positions shown in Fig. 9, breaking the connection between the plugs 19 and p, and the connecting-plug p is electrically connected with the source of electrical supply, as the magneto-generator, (shown in Fig. 10,) to throw current on the called subscribcrs line and ring his local bell. As this operation is but momentary and it is not'desired to allow this call connection to remain subject to the manipulation of a-careless operator, the arrangement for automatically returning the key to normal position is adopted, as before described. WVhen the key is at normal position, the subscribers talk through the cord-circuit including the plug p, contacts 0 c and a a, cord-connectors w and w, and the answering-plug p. The operator may listenin at any time without interrupting the sub- "scribers talking-circuit by throwingthe key to position 2, whereby the operators set is bridged across the line, as will be clear from Figs. '7 and 10.

By arranging the contact-strips in ranges or banks one above the other and employing a key with branches or legs of unequal length I am able to provide a much more compact and simple construction than where the ranges are at opposite ends of the body.

In practical use the plate or body is generally supported upon a horizontal shelf of the switchboard cabinet or structure in substantially the position shown in Figs. 1 and 2, and when so positioned the terminals are arranged in upper and lower banks and with the springstrips in the same vertical planes. The terms upper and lower banks are used herein to relate to the positions of the parts when so horizontally disposed and simply mean that both banks or ranges have a common median plane or line, whether the plate be vertically or horizontally disposed, as it is of-course understood that the body may be disposed vertically upon the switchboard, if desired.

Having described my invention, What I claim 1. In a circuit-changer, a plate, an insulating-base near one end of the plate and carrying ringing and listening terminals arranged in groups, and a key adapted to move in the median line thereof.

2. In a cireuit-changer,a key having depending branches of unequal length movable in a common plane, and ringing and listening terminals on one side of the key in the path of the respective branches.

3. In a circuit-changer, a plate, an insulating-base carrying ringing and listening terminals arranged in banks each having a pair of spring-strips, and a forked key adapted to open one set of strips from the front and the other set from the rear.

L. In a circuit-changer, a plate, an insulating-base supported thereon near one end and carrying ringing and listening terminals arranged in banks, and a forked key supported on the plate 'near its opposite end to change the relations of the terminals of either bank.

5. In a circuit-changer, a plate, a pivoted key, an insulating-base carrying ringing and listening terminals supported in banks having a common median line, said key being forked, one of the branches thereof being at the front of the ends of the terminals of one bank and the other branch being between the terminals of the other bank.

6. In a circuit-changer, a body carrying an insulating-base near one end, ringing and 11sa lower bank of terminals supported on the base, a key extending through the slot and having depending branches of unequal length associated respectively with the banks of terminals.

8. In a circuit-changer, the combination of a body, an insulating-base thereon, an upper and a lower bank of terminals supported on the base, a key pivoted above and extending beneath the body and having a short leg associated with the upper bank and a long leg associated with the lower bank of terminals.

9. In a circuit-changer, the combination of a body, an insulating-base thereon, an upper and a lower bank of terminals, arranged in pairs upon the base, the members of each pair being upon opposite sides of the central line of the body, and a key having branches of unequal length arranged in substantially the said central line and adapted to change the relations of the terminals.

10. In a circuit-changer, the combination of a body, an insulating-base thereon, a bank of terminals arranged upon the base in groups of three upon each side of its central line, a spring-tcrn1inal .of-eaeh group being extended beyond the others, a second bank of lower terminals in groups of two upon each side of the said central line and having a spring-terminal of each group extended to approximately the distance of the first spring-terminals, and a key having a short branch to engage the upper spring-terminals and a long branch to engage the lower ones.

11. In a circuit-changer, the combination with a plate, an insulating-base near one end of the plate, and a forked key pivoted near the opposite end of the plate and having legs of unequal length, of a bank of terminals upon the base disposed in groups of three, one terminal of each group in the line of the short leg of the key, and a second bank of terminals arranged upon the base in groups of two, one terminal of each group being in the line of the longer leg of the key.

12. In a circuit-changer, the combination with an insulating-base, ringing and listening terminals arranged in banks on the base, each bank having a pair of extended spring-strips, of a forked key adapted to move the strips, and means on the key cooperating with one pair of strips to lock the key in listening position and with the other pair of strips to automatically return the key to its normal position when released at the ringing position.

In testimony whereof I affix my signature in the presence of two witnesses.

IN. E. MCCORMICK.

Witnesses:

Ronnn'r K. GUs'rAFsoN, JOSIAH MeRoBER'rs. 

